1. Field of the Invention
The present invention relates generally to resource management and admission control of multimedia data flows and more specifically to management of multimedia data flows that are congested.
2. Description of Background Art
Multimedia data broadcast over an IP (Internet Protocol) infrastructure is a well-known way of transmitting and receiving multimedia data in today's information age. Unlike other forms of data (like text data), multimedia data is dependent upon an uninterrupted, constant flow of data packets (constant bit rate or CBR), to maintain the quality of the data received by an end user. The data packets in a multimedia data flow for standard cable TV viewing proceed through the IP network at a constant bit rate, such as 3.75M bits per second which corresponds to 356 IP packets/second. Multimedia data flow for CATV or HDTV systems is transmitted through the IP network to an end user's set top box (STB). The set top box is designed to receive the multimedia data flow and format the data properly for display on the user's television.
Difficulties arise during management of multimedia data over an IP network during times of congestion. CBR multimedia data over IP networks cannot use conventional congestion control techniques such as RED, WRED, etc. Applying these methods causes severe degradation to all multimedia data flows traversing the link. In conventional systems during periods of congestion, all degraded multimedia data flows are allowed to pass through the IP network and are received by the set-top box. Because the STB is receiving some information, albeit corrupted information, the STB is unable to detect and report a problem to the data sender. Conventional congestion control methods do not always preserve the integrity of any of the multimedia data flows during a period of network link congestion.
What is needed is an efficient means for monitoring and managing congestion of multimedia data flow traffic over an IP network.